X70管线钢在模拟土壤介质中裂纹扩展量化模型

CRACK PROPAGATION QUANTITATIVE MODELS OF X70 PIPELINE STEEL IN THE SYNTHETIC SOIL SOLUTION

试验研究了X70管线钢在模拟土壤介质中 ,循环载荷下的裂纹扩展特性和宏观规律 .结果表明 ,裂纹扩展主要受裂尖应力强度因子幅ΔK的控制 ;在模拟高 pH值 (pH =9 3)土壤介质中 ,加载频率 (0 1Hz～ 10Hz)对裂纹扩展速率无明显影响 ;在模拟近中性土壤介质中 ,裂纹扩展速率随加载频率的降低而升高 ,呈现明显的频率效应 .结合裂纹扩展特性 ,分别建立了X70管线钢在模拟高pH值和近中性土壤介质中 ,加载频率为 0 1Hz～ 10Hz的裂纹扩展量化模型 .

The crack propagation characteristics of X70 pipeline steel in the synthetic soil solution under cyclic loading are investigated.The macroscopical rules of the crack propagation are analyzed as well.Results indicate that the crack propagation is controlled mainly by the crack tip stress intensity factor range Δ K .The loading frequency (0.1 Hz～10 Hz) has little affect on the crack propagation rates in the synthetic high pH soil solution (pH=9.3).The crack propagation rate increases with the decrease of loading frequency (0.1 Hz～10Hz) in the synthetic near neutral soil solution.Considering the cracking propagation characteristics,the crack propagation quantitative models of the loading frequency f =0.1 Hz～10 Hz in the synthetic high pH soil solution and near neutral soil solution are put forward respectively.